2013 Vol. 19, No. 2

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IN-SITU STRESS MEASUREMENT BY DIFFERENTIAL STRAIN ANALYSIS METHOD IN THE WELL TUN-1
BAI Jin-peng, PENG Hua, ZHENG Zhe-xia, LIU Chong, MA Xiu-min, JIANG Jing-jie, LI Zhen
2013, 19(2): 117-124.
Abstract (251) HTML (181) PDF (2831KB)(37)
Abstract:
The principle method of the Differential Strain Analysis technique is briefly recommended. We tested the rock samples taken from the Well Tun-1 which was located in Luoyang-Yichuan basin in Henan Province. The results shows that the maximum horizontal principal stress is NW orientation (141°-157°) in the well of 1153.4~1167.8 m, which is consistent with the maximum horizontal principal stress orientation of the drill collapsing ellipse macro axis. Its value is less than vertical stress, and belongs to normal fault stress. The principal stress increases with depth linearity. Advice for the injection-production well pattern in this area is given, that is the pattern shall not parallel to 141°-157° orientation.
NUMERICAL SIMULATION OF STRUCTURAL STRESS FIELD IN FUNING SEDIMENTARY PERIOD AND PREDICTION OF THE DEVELOPMENT LAW OF LOWER-ORDER FAULTS IN CHAJIAN SLOPE ZONE
FU Xiao-long, DAI Jun-sheng, ZHANG Hong-guo
2013, 19(2): 125-132.
Abstract (173) HTML (95) PDF (5619KB)(9)
Abstract:
Chajian slope zone is located in the south of the western slope, Jinhu sag. It has mainly experienced the Wubao and Sanduo tectonic movements during the sedimentation in Tertiary, which formed the complicated fault system and made it into a complex fault-block reservoir. There are many lower-order faults in this area, which makes great influence to the reservoir description and the development deployment, but they cannot be described correctly only based on the seismic data. The determination of the structural stress direction in Funing sedimentary period, which is NW350°, is based on the areal description of the faults. The method of numerical simulation of tectonic stress was applied to make the geological model and simulate the description of structural stress in Funing sedimentary period. The development law of the lower-order faults was predicted according to the description of structural stress. The results show that the maximum and the minimum principal stress were both in the horizontal direction, which usually forms tenso-shear faults. The development of the lower-order fault is mainly influenced by the difference between the maximum and minimum principal stress and the shear stress. In other words, the difference between principal stresses control the advantage area of the fault development, the plane shear stress control the strike of the fault, and the profile shear stress control the dip direction.
A PRACTICAL ANSYS 3-D NUMERICAL SIMULATION METHOD FOR IN-SITU STRESS FIELD
LIU Ai-hua, YANG Qing, WU Jun-ping
2013, 19(2): 133-142.
Abstract (266) HTML (204) PDF (6853KB)(36)
Abstract:
In-situ stress field, which is consist of self-weight stress field and tectonic stress field, is one of the most important factors in the deep underground engineering analysis. There are some defects in present commonly used three dimensional stress field simulation method, then it is not very well in maintaining ground stress field distribution rule and avoiding additional displacement. Firstly, two methods are evaluated and some Java programming is built based on the better one to create the initial stress file. And that can be done by a simple EXCEL method without programming when higher version ANSYS software is used. Then, a simple node reaction method is put forward to realize ground stress balance which means the displacement in the finite element model is zero. At last, all good methods in the process are integrated into a practical ANSYS 3-D numerical simulation method for in-situ stress field.
CALCULATING MODEL OF EQUIVALENT ROCK MECHANICAL PARAMETERS OF SAND-MUD INTERBED AND ITS APPLICATION
WANG Ke, DAI Jun-sheng, FENG Zhen-dong, XIE Yan-xue, FAN Yang, WANG Yuan, ZHAO Li-bin
2013, 19(2): 143-151.
Abstract (166) HTML (79) PDF (5942KB)(8)
Abstract:
On the basis of the deformation analysis of rocks and on the sense of energy, the general calculating formula of the equivalent rock mechanical parameters is deducted using strain energy theory and energy conservation law, and the logging data calculating model is established. The equivalent rock mechanical parameters of Bashijiqike Formation, the subject reservoir in Kela-A gas field, Kuqa depression, are calculated by the model, and the numerical simulation of stress field and reservoir fractures is carried out on the basis of the calculating result. The simulation demonstrates that reservoir fractures mainly develop on high spot of anticlines and monoclinal structure. This is generally consistent to the current developing practice, and thus the rationality of the model is proved. At last, the advantages and using conditions of the logging data calculating model of equivalent rock mechanical parameters are discussed. It is pointed that the equivalent rock mechanical parameters are suitable for regional and horizontal prediction of stress field and reservoir fractures, not for partial or vertical prediction of distribution regularity of reservoir fractures.
STUDY ON PRESERVED-ORE FACTOR IN XIAZHUANG URANIUM ORE FIELD
ZHANG Wan-liang
2013, 19(2): 152-161, 187.
Abstract (227) HTML (87) PDF (9313KB)(8)
Abstract:
Xiazhuang ore field is the first granite-type uranium ore field found in China, where the deposits and occurrences located in the eastern part of Guidong grante, controlled by structure and lithology. About uranium mineralization type, there are silicified zone type (group vein), intersection type, altered cataclastic rock type and metamorphic sandstone of the outer contact zone of granite. It had experienced the uplifting and exhumating of the crust in the South China during the Cenozoic, specially the late Cenozoic Era after the ore deposits formed. Data integration and field investigation shows that the Shangdong and horse feces Mountain fault are the protection-ore ones. The forming time is newer. The two faults which have together controlled Xiazhuang fault block undercutting, protect the uranium mine not or less being corroded and exhausted. This is why there is ore existing in the east part but not in west of Guidong granite.
GEOCHRONOLOGY AND GEOCHEMISTRY OF THE HEINAOBAO PLUTON IN SIZIWANGQI, INNER MONGOLIA AND ITS TECTONIC EVOLUTION
XIONG Guang-qiang, ZHAO Hong-tao, LIU Min, ZHANG Da, WANG Hao-ran, WANG Zhong
2013, 19(2): 162-177.
Abstract (192) HTML (53) PDF (10253KB)(8)
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Heinaobao granitoid in the Siziwangqi area of Inner Mongolia tectonically belongs to Early Paleozoic hyperplasia plate in the northern margin of the North China plate. The granitiod is predominantly of composed of granodiorite and granote porphyry. The La-ICP-MS U-Pb zircon dating method and petrochemical analysis were used to study and understand its formation age and nature. As a result, zircons from granodiorite U-Pb ages of 407.4±4.7 Ma and 268.0±2.7 Ma, the first age represents the one event of ocean-continent subduction and the second age represents the one event of continent-continent collision. Petrochemistry date indicated that the Heinaobao rock in Siziwangqi belongs to the calc-alkaline series, and gradually near to the hypokalemic Tholeiitic series, depleted in high field strength elements. Geochrono logical and petrochemical data implied that the samples had syn-collisional characteristics. Combined with regional tectonic background, the tectonic background of Heinaobao Sizwangqi is the subduction, collision and docking of Siberian plate and North China Plate, it belongs to Paleo-Asian Ocean tectonic domain, while the late tectonic evolution remains to be further research.
DEFORMATION CHARACTERISTICS AND FORMATION MECHANISM OF XIELIUPO LANDSLIDE IN ZHOUQU
HUANG Xiao, YANG Wei-min, ZHANG Chun-shan, SHEN Jun-feng, LIU Ting
2013, 19(2): 178-187.
Abstract (181) HTML (80) PDF (10951KB)(20)
Abstract:
Based on detailed filed survey and deformation monitoring data for many years, deformation characteristics and formation mechanism of Xieliupo landslide in Zhouqu has been discussed. The result reveal that the landslide which lies in Pingding-Huama Fault Zone belong to a typical giant fault zone landslide being in an unstable state all the time.Xieliupo landslide is formed under the coupling of endogenic and exogenic geological processes.Shattered fault zone is a sufficient condition which resulted in Xieliupo landslide and fault activities lead the slope to plastic flow deformation.Rainfall is a main factor which triggering large-scale slip of the landslide.Furthermore, earthquake, toe cutting and other factors play promoting roles in the landslide's development and evolution.Therefore, further studies on the formation mechanism and disaster pattern of fault zone landslide have important significance towards the prediction and prevention of this type of landslide.
STABILITY RESEARCH OF TANGJIASHAN LANDSLIDE IN WENCHUAN EARTHQUAKE
YUE Gao-wei, LI Wen-zhe, WANG Hui, ZHAO Fa-suo
2013, 19(2): 188-197.
Abstract (139) HTML (77) PDF (7567KB)(17)
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The numerical model of Tangjiashan landslide is established to analyze its slope stability with Mohr-Coulomb theory and the strength reduction method. Firstly, the slope stability is simulated numerically under the natural state (only with the gravity action), and the calculated safety factor is 1.46, which indicates that the slope is relatively stable under the natural state. Secondly, Tangjiashan landslide stability is numerically simulated with large amplitude seismic wave of initial 30 seconds in Wenchuan earthquake, and calculates the free field boundary condition for the slope. The results show that the piercing plastic zone in slope is produced in Wenchuan earthquake, and the simulation plastic zone is good agreement with the real landslide slope body. Because of the earthquake acceleration, larger displacement and velocity of the slope appearing, which produce tremendous energy in the landslide and cause serious disaster and loss.
INSTABILITY MODEL OF VERTICAL LAYER ROCK SLOPE BASED ON THE STATISTICAL CONSTITUTIVE DAMAGE MODEL
LIU Hong-yan, DAN Zengzuoma, LIU Ye, XING Chuang-feng, ZHANG Ji-hong
2013, 19(2): 198-205.
Abstract (143) HTML (67) PDF (1149KB)(18)
Abstract:
According to the actual instability mode of the vertical layer rock slope, the instability calculation model and critical height calculation method under self-gravity load for the vertical layer rock slope on the basis of the Euler pressure bar instability failure method are established. Meanwhile, based on the fact that rock has initial damage, the instability model of the vertical layer rock slope based on the statistical damage model is set up, and the calculation results based on the two models above are discussed. The study result shows that the critical height of the vertical layer rock slope calculated by the method proposed in this paper is about 75% that of other researchers, which is more suitable for the actual loading characteristic and failure condition. The instability model of the vertical layer rock slope based on the rock statistical damage constitutive model not only considers the rock mechanical parameters such as elastic modulus, but also combines the characteristic of the stress-strain curve, from which the calculation result is more suitable for the actual condition. It is also found that the change of the calculation parameters m andε0 has much effect on the calculation results, which indicates that it is very necessary to consider rock damage evolution in the similar problem.
OIL AND GAS CHARACTERISTICS OF THRUSTING-NAPPE STRUCTURE BELT IN HUOYANSHAN, XINJIANG
YAO Hong-xin, LI Wen-sheng, WANG Gen-hou
2013, 19(2): 206-213.
Abstract (245) HTML (115) PDF (2459KB)(19)
Abstract:
Combining the process of structure evolution with oil and gas accumulation, the paper deeply analyzes the evolution, dynamic mechanism, structural model, and its relationship with hydrocarbon accumulations of thrusting-nappe structure belt. The research result shows that constant earthquake created the geochemical environment for generation and migration of hydrocarbon, and the folding movement started in Early Jurassic and the good quality source rocks were the important factors for organic matter evolution and hydrocarbon. Middle Jurassic was the main reservoir intervals and the brown mudstone deposited 800~1000m of Late Jurassic was the regional caprock. Fault-fold tectonic movements provided the force for the hydrocarbon migration. Exploration in the area has been seen lots of oil-gas, mainly with small and medium oil-gas fields. The area between the eastern end of Huoyanshan and Qiketai is the key exploration areas now.
DEVELOPMENT CHARACTERISTICS OF INHERITED FRACTURES IN DEEP SAND-SHALE RESERVOIR
ZHANG Kui-hua, FENG Jian-wei, DAI Jun-sheng
2013, 19(2): 214-224.
Abstract (119) HTML (79) PDF (13101KB)(18)
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Aiming at low-permeability sand-shale reservoir in western compressional basin, with multiple tectonic movements, deep layers, many sale interlayers and high angle fracture network, the fractures not only acts as an effective migration pathway for oil and gas, but also are the main influencing factors to reservoir fracturing development. Taking one of given area for the deep sand shale fractured gas reservoirs before western Tianshan mountain, aiming at bottle neck effect in fracture prediction, carrying out formation mechanism study will be the break through, firstly on the base of core observation, CT computed tomographic scans and imaging logging interpretation, the study subtly statistics fracture occurrences, apertures and packing, then combing fluid inclusion testing and palaeostress field to divide formation times and conclude development models. The result shows that favorable conditions for inherited fractures in sand-shale reservoir are multiple tectonic movements, low stress difference, low approaching angle, appropriate shale content, on the whole, tectonic stress is the external factor, but lithology is the internal cause.